1. Field of the Invention
The present invention relates to an improved package and method for making same for packaging electrical button cells in general and more particularly concerns an impact-resistant handling, shipping and storage package, especially for electric button cells of the metal-air type wherein such cells are packaged to maintain the cells in a sealed condition throughout subsequent handling, shipping and storage.
2. Description of the Prior Art
Packaging devices for button cells are known. U.S. Pat. No. 4,015,708 (assigned to the same assignee as the present invention) describes a storage and merchandising package for battery cells in which cells, such as zinc-air cells, are inserted in apertures and adhesively held against a backing material which, in the preferred embodiment, for zinc-air cells, has preferential barrier properties to extend the shelf life of the cells. The package includes an openable cover which surrounds the cells to prevent accidental shorting or physical dislodgment thereof.
While the various packaging and storage devices of the prior art all provide some advantage over previous configurations, none has solved the problem of providing a package for all types of button cells, including zinc-air button cells, in a manner which provides easy access to the button cells by persons lacking in physical dexterity and of providing an impact-resistant package which may be embodied in a variety of packaging configurations.
The aforementioned patent is directed to a button cell package which has a flat first layer of material having a plurality of apertures dimensioned to receive respective button cells therein. For releasably retaining the button cells in the apertures, a second layer of backing material is laminated to the first layer with pressure-sensitive adhesive on the backing material exposed in the areas underlying the apertures. During packaging, the button cells are firmly pressed against the exposed pressure-sensitive adhesive areas on the backing material. To prevent excessive flexing of the backing material, particularly in the apertures or window areas, the first layer is preferably made of a relatively rigid material, such as card stock, to thereby stiffen the backing material. This substantially precludes warpage of the backing material which tends to separate the exposed adhesive areas from the button cells. Moreover, the first layer and/or the backing material may be formed of a blotter-like material to absorb electrolyte which may leak from the cell. The patent also discloses that the adhesive itself can serve as the barrier member. In that case, the backing material can be made of a gas permeable material such as another layer of paper board or card stock material similar to the first layer.
While the preferred backing material of the referenced patent is a thin polyester plastic film, such as "Mylar", sold by E. I. duPont de Nemours, the packaging has no resilient layer or member in the laminate, nor does the alternative embodiment provide for a resilient layer or member in the laminate. Thus, when the button cells is pressed into the receiving apertures, the button cell surface area in contact with the adhesive layer is dependent upon the compressibility or resiliency of the backing material and upon the shape of the button cell contact surface. Thus, inconsistent and unpredictable degrees of adherence result between the button cell and the adhesive layer when the cell is compressed against the relatively incompressible paper board or card stock. This may result in cells inadvertently separating from the adhesive layer and, in the case of metal-air cells which depend upon good adherence to the adhesive layer to maintain the cell in a sealed condition, will prematurely reduce cell shelf life as the result of oxygen, carbon dioxide or moisture in the air entering the cell, or moisture escaping from the cell, resulting in the possibility of a dead cell when subsequently placed in service by the consumer.
Previous button cell packaging configurations are not readily adaptable for packaging all types of button cells and are generally unacceptable from the viewpoint of cell accessibility and ease of cell removal, or are unacceptable because cells may easily become dislodged and lost during handling or shipping and do not adequately protect metal-air cells to prevent inadvertent and premature loss of cell capacity.
The present invention greatly reduces the possibility of a button cell becoming inadvertently dislodged or lost, or, in the case of a metal-air cell, premature loss of cell capacity. This is accomplished by utilizing a laminated structure which includes a resilient member between a pressure-sensitive adhesive surface layer and a nonresilient base member. When the button cell is pressed onto the adhesive layer, the resilient member serves as a cushion and deforms or yields to the shape of the button cell contact surface to maximize the contact area between the cell contact surface and the adhesive surface layer, thus providing a reproducible and reliable adhesive contact between the cell and the adhesive layer, regardless of the shape of the button cell contact surface. The present invention also provides a basic button cell package which has sufficient impact resistance to withstand rough handling without cell dislodgement, thereby permitting button cells of any type to be commercially packaged in a wide variety of package or housing configurations, including reclosable housing configurations which provide easy access to and removal of the individual cells by persons lacking in physical dexterity.